As is known, a coke oven gas-collecting system includes an ascension pipe, leading from a coking chamber, which is connected through an elbow to the gas main for the coke oven installation. A nozzle projects through the top wall of the elbow and is used not only during operation of the ovens for the introduction of an ammonia-containing liquid but also to extract, with the use of high-pressure steam, the gases evolved during charging which pass upwardly through the top gas-collecting chamber and the ascension pipe into the main.
It is important that all gases which evolve during charging of the oven chamber be collected completely such that they do not escape into the atmosphere. For this reason, it is necessary to produce a very strong suction in the elbow leading to the main by means of the steam passing through the aforesaid nozzle.